Common CCD black and white camera can experience smooth spectral character, it can experience visible light not only, and can experience infra-red light. This uses common CCD namely black and white camera, cooperate infra-red lamp to be able to compare economic ground to realize the fundamental that night inspects. And the spectral character of common color camera cannot experience infra-red light, because this cannot be used at night,inspect.
Infra-red lamp presses his cent of mechanism of infra-red ray radiation gives off light for semiconductor solid (infra-red emissive diode) infra-red lamp and heat radiation are infra-red the lamp two kinds. We introduce its principle and character as follows:
1. Infra-red emissive diode (LED) the principle of infra-red lamp and character
Comprise illuminant by matrix of infra-red glow diode. Infra-red emissive diode by the stuff with infra-red radiate expensive efficiency (commonly used arsenic changes gallium) make PN written guarantee, adscititious arousing infra-red light to electric current of PN knot infuse to bias voltage. Spectral power distributings for 950nm of ～ of central wavelengh 830, half peak bandwidth makes an appointment with 40nm left and right sides, it is tape distributings, for the range that common CCD black and white camera can experience. Its biggest advantage is OK do not have completely red cruel, (use wavelengh of 950nm of 940 ～ infra-red canal) or only and faint red cruel (red cruel to have visible glow) grow with life.
The emissive power of infra-red glow diode expresses with W/m2 of irradiation level μ . Generally speaking, its are infra-red radiation power and becoming direct ratio to working electric current, but be close to when the biggest rating to electric current, the temperature of parts of an apparatus rises because of voltaic hear rate, make smooth emissive power drops. Infra-red diode electric current is too small, the play that affects its radiate power, but working electric current crosses a general to affect its life, make even infra-red diode burn down.
Cross when voltage to threshold value voltage (make an appointment with 0.8V to control) electric current begins flow, and be one very steep straight curve, show its work electric current is very sensitive to working voltage. Because this asks working voltage is accurate, stable, affect the play of radiation power and its reliability otherwise. What radiation power follows environmental temperature is elevatory (the environmental temperature that the calorific place that includes its itself produces is elevatory) can make its radiate power drops. Infra-red lamp especially remote infra-red lamp, hear rate is the problem that design and should note when the choice.
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